The invention relates to automatic fire protection sprinkler heads.
As is well known, automatic fire protection sprinkler systems typically consist of a piping system extending throughout the building to be protected, with automatic sprinkler head outlets positioned along the piping in a configuration to help protect life and property in case of fire. Automatic sprinkler heads utilize a valve element which is normally maintained in a stand-by (closed) position by thermally responsive means, e.g., a fusible link, frangible bulb or other thermal element. When the surrounding air temperature causes the temperature of the thermal element to increase to its release temperature, the valve element is caused to open to release fire-retardant fluid, typically water.
In warehouses and other premises where aesthetic appearance is not a consideration, sprinkler heads are usually fully exposed. However, in applications such as offices, hotels and residences, it has often been desirable to arrange the fire protection sprinkler system piping above the ceiling and to employ pendent sprinkler heads which for the most part are hidden above the lower plane of the ceiling, or to arrange the piping behind the walls and to employ recessed sprinkler heads which are for the most part hidden behind the plane of the wall.
Two types of pendent sprinklers for ceiling applications are referred to by the terms "concealed" and "flush". A concealed sprinkler has its entire body, including the thermally responsive element which releases the valve, located above the lower plane of the ceiling and hidden from view by a concealing plate located just beneath the ceiling. Prior patents illustrating this type are Juliano U.S. Pat. No. 3,998,273; Anderson U.S. Pat. No. 4,066,129 and Mears U.S. Pat. No. 4,215,751.
A flush sprinkler head has the majority of its body located above the lower plane of the ceiling while the thermally responsive element is located below the ceiling. Prior patents illustrating this type are Winslow U.S. Pat. No. 2,271,399; Tyden U.S. Pat. Nos. 2,389,331 and 2,389,332; Campbell et al. U.S. Pat. No. 3,195,647 and Miyazaki U.S. Pat. No. 4,217,960.
The concealed sprinkler head is less obtrusive and generally regarded as more attractive than the flush sprinkler head. Unfortunately, the temperature of its thermally responsive element rises more slowly when heated air currents occur, and therefore it has a relatively lower speed of response.
For sidewall sprinkler heads there is a similar need for a construction that enables good appearance and fast response to be achieved.
It is the object of this invention to provide an automatic sprinkler head which enables good appearance and quick response, and is at the same time reliable and practical to produce. A further object is to provide an improved sprinkler head construction which is more generally useful in other types of sprinklers.